Method of manufacturing a container with improved wall uniformity and reduced material

Abstract

A method of manufacturing a container, wherein less material is required to produce the container, the container has a more uniform wall thickness, and malformations around the neck of the container are significantly reduced. The method includes forming plastic into a parison and blowing it into a mold having a tapered neck portion and a body portion, which join to form an annular corner for contacting the parison. A blow pin blows air into the mold and parison, causing the parison to expand and conform to the inner contour of the mold. The taper of the neck portion and the annular corner thereby formed, cool the plastic at that point and more uniformly form the parison into the container, the amount of material wasted and required in manufacturing the container is substantially reduced, as is malformations and warping which usually occur about the neck of the finished container.

What is claimed is: 
     
       1. A method of forming a container from plastic, comprising the steps of: heating and forming the plastic into a parison;   enclosing said parison within a mold, said mold comprising a body portion and a neck portion having a top end and a lower end, said neck portion being tapered such that an inner diameter of said top end is greater than an inner diameter of said lower end, said neck portion defining an annular edge with said body portion;   blowing areas into said parison to shape said parison within said mold;   contacting, and pinching said parison with said annular edge so that said parison is contacted substantially only by said annular edge said contact substantially centering said parison within said neck portion of said mold, said pinching thereby stretching ad-thinning the parison at the annular edge;   cooling said parison at said annular edge;   completing the formation of said container by conforming the plastic to said mold by blowing the plastic in the panson proportionally more in said body portion than in said neck portion thereby distributing plastic in said mold.   
     
     
       2. The method as described in claim 1 wherein the plastic is heated to a temperature within the range of 310° to 320 degrees Fahrenheit.